Heads Warped on 2004 Ford F-350 Super Duty

The truck ws operation on I 45 north when it begain to slow down from 65mph. Continued to slow with white smokie out the tail pipe. Mecdhanic advises it must be warped heads. This truck has a desel enging and they are talking $5.000 to fix it. Anybody got another idea

Absolutely get a second opinion. These engine have an EGR cooler that when failure occurs, have the exact same symptoms as a blown head gasket due to the fact that it allows coolant to enter the combustion chamber as a failed head gasket will do. I have vast experience with this engine and see maybe one time out of twenty with failed head gaskets- sometimes cracked heads, but rarely warped. The test procedure involves replacing the EGR cooler first, then retesting for head gaskets with a coolant pressure gauge. If the repair facility does not have a good working knowledge with this engine, do not let them practice on yours.